I find the Trend Power Strategy very useful for finding possible reversal trades and continuation trades but I have found that sometimes the arrows move to the next candle. I have not found that the signal changes. I have not seen a red sell arrow change to a blue buy arrow. Look at the two charts for the AUDUSD and you'll understand what I mean. The first is a screenshot taken on 19 January 2018 and the second was taken on 24 January 2018.